The present invention relates to an installation structure of a pressure control valve that functions to prevent hydraulic surge under low temperature by maintaining a discharge pressure of an oil pump at a predetermined value, and more particularly to an installation structure of a relief valve for a toroidal type continuously variable transmission (CVT) applied to a rear-wheel drive vehicle.
Conventional automatic transmissions for rear-wheel drive vehicles have been generally arranged to dispose a transmission control valve assembly under a transmission mechanism. Further, a relief valve for maintaining an oil discharge pressure of an oil pump is generally disposed at a lower surface of a transmission case so as to be directed toward an oil pan. In view of preferably preventing hydraulic surge under low temperature, it is preferable to employ a large size relief valve.